Intermittent fasting
I don’t endorse most diets. Why? They simply don’t work. In the short term (within the first month), you are likely to achieve some weight loss (much of which is water); but in the longer term sustainability and adherence become challenging.
There is, however, an exception: intermittent fasting.
The benefits
This is not so much a ‘diet’ as a way of eating where you mainly restrict the hours of feeding. The scientific evidence shows that intermittent fasting not only results in sustainable weight loss, especially in the dangerous abdominal area [it achieves greater reductions in body fat when compared to continuous caloric restriction], but it also has so many other health benefits: increased longevity and improved ageing, reduced inflammation, blood glucose and blood pressure. It also helps the brain function better with improved cognition, memory and learning, it prevents neurodegeneration (delays dementia) as well as has an anti-depressant effect. Research shows that it activates pathways which defend us against oxidative and metabolic stress, improves immune regeneration while removing and repairing damaged cells and molecules.
How does this happen? The body switches from its normal fuel source of glucose to burning fatty acids and ketone bodies instead, which increases our metabolic flexibility. Fasting sends hunger signals to the brain; when these are ignored, the body interprets the situation as famine and switches from growth to repair mode. This triggers something called autophagy which is where old and damaged cells are broken down and recycled. New cells grow faster and stem cells are activated. Fasting reduces IGF-1 levels in the body. This is a hormone that triggers cell growth. Therefore fasting may reduce excess cell proliferation and hence cancer growth. Fasting prior to – and during – chemotherapy seems to protect the healthy but not the cancerous cells, thereby making the treatment more effective. It also seems to reduce the side effects of chemotherapy such as nausea and vomiting.
Insulin not only regulates blood sugar, but it also increases cell turnover and inhibits the breakdown of fat. Fasting lowers insulin levels, improves insulin sensitivity and blood glucose regulation, and hence may reduce the risk of type 2 diabetes. It also breaks down fat for energy better than with continuous caloric restriction.
Fasting lowers blood pressure and reduces blood lipid levels including cholesterol, thereby reducing the impact of cardiovascular disease particularly ischaemic strokes. It has also been shown to improve the symptoms of inflammatory conditions such as allergies, asthma and psoriasis.
How to do it
There is nothing new about fasting, it has been around as long as humans have walked the earth. Humans evolved in an environment where food was scarce, in contrast to our state of food abundance today. Our ancestors often experienced times of food deprivation and many of the world’s religions incorporate periods of fasting to purify the mind and body. But the concept has been reworked in many forms to make it more adaptable and approachable for modern times; and if you do it correctly, you won’t even feel hungry. In fact many of you are probably already doing it without realizing.
The key is to find a style of eating (not dieting!) that works for you. At its simplest, you take a break from eating between dinner and breakfast. You stop eating at 7pm and resume again at 7am. Fasting for 12 hours during this time is in line with our natural circadian rhythms; ie we eat when the sun is up and stop when the sun goes down. A 12 hour fast is healthy for anyone and gives your digestion a break so the body can focus on rest and repair.
The 16:8 is when you elongate your nightly fast to 16 hours between dinner and breakfast. For example you eat an early dinner around 6pm and then a late breakfast at 10am. Many people find doing this for a few days each week to be beneficial.
The most popular ‘diet’ today is the 5:2 diet: you eat normally for 5 days of the week and then restrict your calories to approximately 25% of your total normal calories for the other two, preferably non-consecutive, days. It’s important to eat healthily on the fast days and not to over-eat on the non-fast days. On fast days, the restricted calories can be eaten at any time, but 1 or 2 meals with a long break in between showed the best results.
Other approaches with proven safety and efficacy include time-restricted eating where you only eat within a 6 hour window during the day, for example 12-6pm; or a 8 hour window of 11am–7pm. Again it’s important to ensure that you fuel your body with nutrient-dense foods during this window, and not empty calories or low-quality foods.
Complete alternate day fasting is when you do a 24 hour fast on one or two chosen days of the week.
On a fasting mimicking diet you reduce caloric intake to 30% of your requirement for 5 consecutive days before returning to normal eating patterns. This cycle can be repeated once a month or once every 3-4 months per year.
Compliance
Intermittent fasting may also be more successful because it is easier to stick to: it’s simple, flexible, and easy to follow. It is also less emotionally demanding and socially inconvenient.
Who should not fast
Fasting is generally safe with no major adverse effects, providing it is being done by an adult in relatively good health. Minor reported side effects include: insomnia, irritability, dizziness, headaches and low energy on fast days.
Fasting should be avoided by:
· Children, teenagers and the elderly
· Pregnant women
· Anyone who is underweight or has a history of eating disorders
· Anyone who has been suffering from chronic stress for some time
· Type 1 diabetics
· Anyone who is unwell or has a fever
· Always check with your doctor if you are taking any medication.
